Grinding wheel



April 28, 1936. H, D, EY R 2,038,727

GRINDING WHEEL Filed June 20, 1935 1 2 Sheets-Sheet l I INVENTOR 7; 4 I I I fgzrvepl H 559 51 TTORNEYS April 1936; H. D. GEYER 2,038,727

GRINDING WHEEL Filed June 20, 1935 2 Sheets-Sheet 2 46 42 Her vegi jyer 75} Q/ w/JMM HIS ATTORNEYS Patented Apr. 28, 1936 PATENT OFFICE GRINDING WHEEL Harvey D. Geyer, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application June 20,

5 Claims.

This invention relates to rigid abrasive bodies, such as grinding wheels of carborundum, emery, or other well known abrasive materials, and means for securely fixing such abrasive bodies 5 upon a supporting metal back plate or other metal support for the non-metallic abrasive material.

An object of this invention is to provide an improved means and method for rigidly fixing such 10 abrasive bodies to a supporting metal back plate, such as steel, which will give greater surety against the abrasive body, such as a grinding wheel, breaking apart and flying off when rotated at very high speeds in use. This provides greater safety for the operator.

Another object of the invention is to provide means for mounting disk grinding wheels upon the metal back plate which fixes the wheel to its rotating shaft, which means will permit the use of the wheel when it is worn to a smaller thickness than is permissible with such disk grinding wheels mounted by means new in general use.

Further objects and advantages of the present invention will be apparent from the following description; reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a face view of a finished disk grinding wheel bonded to its supporting back plate according to this invention.

Fig. 2 is a section taken on line 2-2 of Fig. 1.

Fig. 3 illustrates a step in the method of this invention, and shows the spray-coating of the back surface of the abrasive wheel.

Fig. 4 shows the coated abrasive wheel and the coated metal back plate with their coated surfaces in juxtaposition, illustrating how these two coated surfaces are applied'one to the other prior to the bonding step of the method.

Figs. 5 and 6 illustrate in a diagrammatic manner an apparatus which may be used for carrying out the bonding step of the method.

Fig. 5 is a plan view of a turn-table which holds the abrasive wheel and its back plate in assembled position during the heating step and during the pressing and cooling step of the method.

Fig. 6 is a; vertical section taken on line 6Ii of Fig. 5 and shows both the position of the wheel as-. sembly during the heating step and during the pressing and cooling step.

Similar reference characters refer to similar parts throughout the several figures of the drawings.

I II designates the rigid non-metallic abrasive 1935, Serial No. 27,477

wheel itself, which may be of carborundum, emery, or any other similar and well known abrasive material.

I I is the supporting metal back plate to which the abrasive wheel I is strongly surface bonded by means of the intervening metal layer I2 which adheres very strongly both to the contacting surface of wheel I0 and the plate II. Plate II is preferably of steel and is shown as having an integral hub I3 by which the wheel assembly may be 10 suitably fixed to its rotating shaft. Of course plate II may be a flat plate bolted or otherwise suitably fixed to a separate hub member. This invention relates only to the means and method of securely fixing the abrasive body I0 to the adjacent surface of plate II.

In following the method of this invention, the back surface of the abrasive wheel I0 is first spray coated with molten metal which may be lead, tin zinc, copper, or other suitable metal or a suitable alloy of such metals, to form the relatively thin strongly adhering metal coating I5 shown in Fig.

4. A coating I 6 of a similar suitable metal is also applied to the surface of plate II which is to be bonded to the wheel It). The abrasive wheel I0 and the metal plate II, having been thus coated with the relatively thin coats I5 and I6 respectively, are then assembled together in the proper relative positions and heated to a temperature suflicient to soften or fuse the two metal coats I5 0 and I6 and pressure is applied to force the two coated surfaces I5 and I6 together while they are in an alloyable or fusible condition, and they are then cooled while this pressure is being maintained. This results in the two contacting coats I5 and I6 being firmly bonded together in a manner similar to soldering. When this is done the non-metallic abrasive wheel I0 is strongly bonded to the metal back plate I I and the wheel is ready for use.

Fig. 3 shows one apparatus and method of spray-coating the abrasive wheel III with the spray coat I5. The supply of liquid coating metal 20 for forming the spray coat I5 is maintained in molten condition in container 2| by a suitable gas burner 22. Directly above contamer 2I is mounted a rotating shaft 23 having a series of thin metal spraying disks 24 fixed thereto, these disks being of a metal, such as steel, having a. melting point sufliciently high to prevent damage thereto by insertion in the molten metal 20. The level of the molten metal 20 is kept at such a point that the lower portions of disks 24 are immersed therein. Now when shaft 23 is power driven at a suitably high speed the disks 24 will pick up the molten metal and throw it off radially in fine particles thus giving something which may be called a metal'mist 25. The wheel I0 is rotatably mounted upon the journal 28 directly in the path of the metal spray 25, hence when wheel I0 is slowly rotated about journal 26 by any suitable means (not shown) the under surface thereof will be coated with a uniformly applied spray coat It. The fine metal particles are thrown by centrifugal force with high speed against the normally rough surface of the abrasive body I. while they are yet plastic and hence these metal particles penetrate into the smallest crevices and minute cavities in the abrasive material and upon immediately solidifying therein are firmly locked or keyed to the abrasive material. By thus substantially keying the first layer of individual small particles of metal to the abrasive surface and subsequently keying these first applied particles of metal to each other by the particles thrown later against them to form the coating I, it has been found that such coating l5 will adhere very strongly to the abrasive material and cannot be stripped therefrom without shearing the metal itself. It is desirable to spray the metal particles from disks 24 through an atmosphere of non-oxidizing or reducing gas in order to prevent partial oxidation of the particles during transit or after they have been deposited upon the abrasive material. For this purpose the housing is preferably kept filled with a suitable non-oxidizing or reducing atmosphere during the spraying operation. The chamber 21 is maintained heated to a suitable temperature by any suitable heating means, such as by the electric heating coils 28. As soon as the sprayed metal particles pass out of chamber 21 through the opening 29 they cool rapidly and hence substantially immediately solidify upon striking the relatively cool abrasive wheel ill.

The metal coating I8 is separately applied to the metal back plate II by any simple and well known method, such as by dipping the suitably cleaned and fluxed plate ll into molten metal and immediately removing same. Preferably a number of grinding wheels III and backing plates I I are coated with coats I5 and I 6 respectively, and these parts are subsequently assembled together to form the units shown in Fig. 2 by the bonding operation illustrated in Figs. '5 and 6.

Fig. 5 shows a tum-table ll for supporting and handling a series of grinding wheels l0 when set loosely upon their back plates ll during the heating step and also during the compressing step of the bondinpoperation. Turn-table 40 has aseries of radial arms if each having an end fork 42 thereon adapted to receive the hub portion II when the back plates II are set upon the ends of arms 4| with the wheels III thereupon as shown in Fig. 5. While the loosely assembled units Ill and II are in the two positions A and 3" of Fig. 5, the desired amount of heat is applied by the small gas burners 43 to bring the metal coatings l5. and II up to the desired bonding temperature.- The loosely ,as-

sembled unit is then shifted to position "6 where it is located between the press plunger 45 and press table ll. At this point press plunger ll is caused to descend upon the top surface of wheel I! and thus press the contacting metalooated surfaces of wheel II and plate II together while the metal coatings II and I 6 thereon are in a soft or semi-plastic state., These upon cooling while the pressure of plunger 45 is being maintained. The press plunger 45 is then raised and the now assembled wheel unit shifted to position D of Fig. 5, where it is removed as the finished unit shown in Fig. 2.

While the apparatus shown in Figs. 5 and 6 heats the metal coatings l5 and I6 to the desired point prior to the main pressure being applied to bond these coatings together, if desired the heating step and pressing step of this invention may be carried on simultaneously. However it is preferred in any case to maintain the application of the pressure until the bonding coating has solidified by cooling.

While this method has been illustrated and described in connection with bonding-a disk grinding wheel to its supporting back plate, it is readily adaptable for use in bonding other kinds of grinding wheels or non-metallic abrasive bodies to shafts or metal adapters of any desired design, or for bonding any other ceramic or similar body such as tile to a supporting metal sheet or plate.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope-of the claims which follow.

What is claimed is as follows:

, 1. A grinding wheel of non-metallic abrasive material having a metal support therefor surface bonded thereto over substantially the entire radial surface on one side of said wheel by means of an intervening metal layer which adheres strongly to both the abrasive material and said metal support.

2. The steps in the method of rigidly fixing a rigid non-metallic abrasive body to a metal back, comprising: providing a strongly adhering spray coat of relatively low-melting metal upon said abrasive body by throwing fine particles of molten metal with high speed against said body and thereby causing strong adherence of said spray coat, providing a relatively low-melting metal coat upon said metal back, then pressing the abrasive'body against the metal back in such manner as to bring their coated surfaces into intimate pressure contact at a temperature sufilcient to partially fuse and bond said contacting metal coats together, then cooling the assembly while maintaining said pressure contact.

3. The steps in the method of rigidly fixing a rigid non-metallic abrasive body to a metal back, comprising: providing a strongly adhering, relatively thin metal coat upon said abrasive body,

providing a relatively thin metal coat upon said metal back, said metal coats both having-a lowermelting point than the metal of said back and having a bonding ,afilnity for each other, then pressing the abrasive body against the metal back in such manner as to bring their coated surfaces into intimate pressure contact at a temperature 'sufiicient to bond said contacting metal coats together, then cooling the assembly whilev maintaining said pressure contact.

4. The steps in the method of rigidly fixing an abrasive grinding wheel upon a metal back plate, comprising: spraying molten metal upon one surface of said wheel to give it a relatively thin strongly adhering metal coat, separately providing a relatively thin metal coat upon said metal back plate, both of said metal coats having a lower melting point-.than the metal of said, back plate, then pressing the coated surface of the grinding coatingsarestronglybondedorailoyedtogether wheel against of the back 76 plate at such a temperature as will fuse or alloy said two contacting metal coats together and provide a strong metal bond between said grinding wheel and back plate.

5. The steps in the method of rigidly fixing a ceramic body to a metal back, comprising: providing a strongly adhering relatively thin metal coat upon said ceramic body. providing a relatively thin metal coat upon said metal back, then pressing the two metal-coated surfaces of said ceramic body and metal back together at a temperature suflicientiy high to stronglybond said 5 

